A plug and a socket that are attached to a container for storing a liquid, such as a chemical solution, which is used for semiconductor production, are known (for example, see Japanese Unexamined Patent Application, Publication No. 2009-173326).
The plug and the socket that are disclosed in Japanese Unexamined Patent Application, Publication No. 2009-173326 pressurize the inside of the container with a gas supplied from a gas supply tube to the socket, and guide the liquid stored in the container to an outside conduit through a siphon tube, the plug, and the socket.